Question

The number of items on two grocery lists differs by 9. The total number of items for both lists is 33. How many items are on each list?

Answer 1

Let b>a

b-a=9

b=9+a

...

a+b=33, using b found above in this we get:

a+9+a=33

2a+9=33

2a=24

a=12, and since b=9+a

b=21

So there are 12 items on one list and 21 items on the other list.